Tread portion of an automobile tire



FIG. 1 is a front view of a tread portion of an automobile tire;

FIG. 2 is a perspective view thereof;

FIG. 3 is a left side view thereof; and,

FIG. 4 is a fragmentary enlarged view showing the details of the tread portion thereof.

The broken lines defining the sidewall and inner bead of the tire depict environmental subject matter that forms no part of the claimed design. 

The ornamental design for a tread portion of an automobile tire, as shown and described. 